Spring中Bean重复注入问题

其实本质上只是easypoi:4.0.0这个jar自己就会发生冲突，主要是下面两个类之间的冲突

 
 	cn.afterturn
 	easypoi-spring-boot-starter
 	4.0.0
 
 
 		
 	org.springframework.boot
	spring-boot-starter 
 	2.4.4
 

The bean 'beanNameViewResolver', defined in class path resource [cn/afterturn/easypoi/configuration/EasyPoiAutoConfiguration.class], could not be registered. A bean with that name has already been defined in class path resource [org/springframework/boot/autoconfigure/web/servlet/error/ErrorMvcAutoConfiguration$WhitelabelErrorViewConfiguration.class] and overriding is disabled.

找到easypoi-spring-boot-starter:4.0.4的中cn.afterturn.easypoi.configuration.EasyPoiAutoConfiguration类中方法beanNameViewResolver注入BeanNameViewResolver类型的Bean

@Bean
public BeanNameViewResolver beanNameViewResolver() {
    BeanNameViewResolver resolver = new BeanNameViewResolver();
    resolver.setOrder(10);
    return resolver;
}

再找到spring-boot-autoconfigure:2.4.4中org.springframework.boot.autoconfigure.web.servlet.error.ErrorMvcAutoConfiguration中的内部类WhitelabelErrorViewConfiguration中有方法beanNameViewResolver注入BeanNameViewResolver类型的bean

@Bean
@ConditionalOnMissingBean
 public BeanNameViewResolver beanNameViewResolver() {
     BeanNameViewResolver resolver = new BeanNameViewResolver();
     resolver.setOrder(2147483637);
     return resolver;
 }

经过我一番查找发现这两个方法注入的是同一个org.springframework.web.servlet.view.BeanNameViewResolver类型的bean，该bean在spring-webmvc-5.3.5.jar下。springboot给出了解决重复注入bean的提示如下

Consider renaming one of the beans or enabling overriding by setting spring.main.allow-bean-definition-overriding=true

大致意思是说在配置文件中开启同一个bean重复注入时与许最后一个注入的bean覆盖掉前面的注入的bean
后来在bean文件中加入如下配置

spring:
  main:
    allow-bean-definition-overriding: true    # 开启一样的bean的覆盖注入,后定义的bean会覆盖之前定义的相同名称的bean。

加入该配置后项目启动成功。